The present invention relates to a method and apparatus for treating blood for the removal of substances therefrom. This invention is directed to both post-operative and intra-operative blood treatment.
In both intra-operative and post-operative blood removal for autotransfusion, it has been found necessary to find some means to cause the blood to resist coagulation, because of the risk of clot formation resulting in harm to the patient upon autotransfusion. Largely, attempts at resisting coagulation have resulted in an anti-coagulant drug being injected into the container in which blood is being collected for re-use. Between intra-operative and post-operative blood re-use, post-operative blood collection for re-use has had increased medical interest, because the blood is generally freer of debris, contaminants and the like.
While there have been differing views on the extent to which anti-coagulants are necessary in post-operative blood collection for autotransfusion, the use of anti-coagulants has at least been a serious consideration, with due regard to individual predisposition to clotting, to the various operations/procedures being undergone by a patient which may affect on a relative basis the individual's ability to clot, and to the different procedures/operations as regards the likely rapidity of blood loss (loss rate).
It has been known, with regard to the above considerations, to adjust the anti-coagulant to these various factors.
It is also known that the injection of anti-coagulant into the blood, by means of injecting it into the container in which the blood is collected for re-use, or even the injection of anti-coagulants directly into the patient, can cause certain disadvantageous effects. One of these is citric toxicity. Another is an undesirable imbalance in pH (acidity/alkaline level of the blood). Yet another is dilution of the blood by the anti-coagulant, depending upon the blood condition at any given time. Yet another deficiency of using an anti-coagulant drug, is that the same must be periodically mixed. Another deficiency of using an anti-coagulant is the necessary careful control of the amount that is being added to the blood, which would vary depending upon the amount of blood being collected, among other variances.